Lancet assembly

ABSTRACT

A lancet assembly includes a reusable base unit that defines a handle for a lancet assembly and houses a biasing mechanism for driving a lancet into the finger of a user. The base unit includes a spring biased hammer that once cocked, can be released to drive a lancet. A lancet is included in a disposable end cap that may be releasible attached to one end of the base unit. The end cap includes integral resilience spring fingers that maintain the lancet completely within the end cap before and after use, and functions to return the lancet after engagement of the lancet and hammer. The end cap can be rotated to orient the end cap relative to user&#39;s finger to control the depth of penetration of the lancet into the user&#39;s finger.

This is a division of application Ser. No. 367,862, filed on June 19,1989, now U.S. Pat. No. 4,990,154.

BACKGROUND OF THE INVENTION

A. Field of the Invention.

The device of the present invention generally relates to a new andimproved lancet assembly for puncturing the skin of a user to obtain ablood sample; and, more particularly, to a new and improved lancetassembly including a disposable end cap containing a one piece lancet.

B. Description of the Prior Art

Sharp pointed lancets are employed to make a puncture or penetration ofa patient's skin in order to provide a small outflow of blood. Varioustests may be employed with only small amounts of blood so that bloodflowing from a finger prick is normally sufficient for these tests.Tests on the blood sample often include contacting a paper strip orreagent pad on a strip carrying chemistry with blood from the wound orpuncture.

Lancet assemblies now available include a driving member that grips alancet. Loading and removing a lancet from the driving member of theassembly requires extra care by the user to avoid being punctured. Thelancet must be carefully gripped to avoid contact with the sharp end ofthe lancet. Present day concerns about communicable diseases transmittedthrough body fluids such as blood increases the risks of handling theselancets.

Current devices require the user to remove a protective cover from thesharp end of a lancet, and load the exposed lancet into a lancetassembly. After use of the assembly, the point of the lancet is exposed.Users of these devices, such as nurses, are repeatedly handling theseused, exposed lancets and have a high risk of puncture by a used lancetand resultant exposure to contamination through the blood on the lancet.

Some designs of lancets include a end cap with the sharp end of thelancet contained within the end cap after use, and the opposite end ofthe lancet sticking out of the end cap. Upon removal of the end capafter use, it is possible for the user to be stuck with an infectedlancet simply by pressing on the exposed end of the lancet therebymoving the sharp end of the lancet out of the end cap. This risk isespecially high for professional users such as nurses who place usedlancets in their pockets. At the end of the day the nurses reach intotheir pockets and pull out used items including lancets. Upon reachinginto his or her pocket, the nurse can press the back end of a lancetthereby exposing the contaminated sharp point.

One example of a known lancet is illustrated in U.S. Pat. No. 3,030,959.The lancet of this patent includes a spindle designed for housing areplaceable magazine containing a stock of needles. A feeding device forfeeding a needle to be used is also disclosed. After a needle is used,it is maintained in the lancet until another needle from the magazine isloaded. As the new needle is advanced, the needle preceding it isejected from the lancet. The lancet assembly of U.S. Pat. No. 3,030,959ejects an unprotected, exposed and contaminated needle which increasesthe risk of puncture by the user of the lancet assembly.

A disposable needle probe package is disclosed in U.S. Pat. No.4,637,403. The needle package is frictionally held in the medicaltesting system by snapping, threading or similar procedures, and it isreleasable by pushing the probe package out of the medical monitoringsystem. Once the probe package is released from the monitoring system,however, the needle is exposed and handling can result in puncturing theskin of the user thereby exposing the user to contaminated blood.

A lancet assembly intended to be disposable with no part of the assemblyreused is disclosed in U.S. Pat. No. 4,375,815. Examples of other lancetassemblies intended to be totally disposable, as opposed to disposingonly the lancet, are disclosed in U.S. Pat. Nos. 4,388,925; 4,553,541;4,449,529 and 4,535,769.

A disposable lancet defined by a plunger is disclosed in U.S. Pat. Nos.4,712,548 and 4,738,261. After this device has been used, the lancet isexposed with the risk that someone handling the used device could bepunctured by the contaminated lancet.

Lancet assemblies in which used, exposed lancets must be removed withthe risk of puncture are disclosed in U.S. Pat. Nos. 4,416,279;4,462,405; 4,442,836 and 4,469,110.

U.S. Pat. No. 4,545,376 discloses a one piece, plastic lancet consistingof a handle and a tip. Once a protective yoke is removed, the lancet tipis completely exposed and can accidentally puncture a user.

Lancet assemblies that are totally disposable with no reusablecomponents are disclosed in U. S. Pat. Nos. 4,624,253; 4,616,649 and4,539,988.

A lancet assembly with a lancet exposed after use is disclosed in U.S.Pat. No. 4,452,243.

Some lancet assemblies provide for the depth of penetration of thelancet into the skin of a user or patient to be adjustable.Adjustability has been accomplished in some prior art lancet assembliesby using removable end caps. Typically, prior art lancet assemblies canbe used with one of two end caps each having different size holesallowing different amounts of the skin of the finger to be contacted.With a greater amount of skin fitting into the hole, the lancet canpierce deeper into the skin of the finger. With a lesser amount of skinfitting into the end cap through the hole, a shallower piercing willoccur.

There is a need for a lancet assembly in which the lancet is completelycontained within a portion of the lancet assembly both before and afteruse such that the user can dispose of the lancet without risk ofpuncture. There also is a need for a lancet assembly that is easily andquickly adjustable to control the depth of penetration of the lancetinto the finger of a user or patient. In addition, there is a need for alancet which is as painless as possible.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new and improvedlancet assembly for piercing the skin of a user to extract blood fortesting purposes.

Another object of the present invention is to provide a new andimprovement lancet assembly that can be easily adjusted to control thedepth of penetration into the skin of the user.

A further object of the present invention is to provide a new andimproved lancet assembly that includes a disposable, easily detachableend cap in which is totally contained a lancet that is not exposedbefore or after use.

A still further object of the present invention is to provide a new andimproved lancet assembly that includes a molded, one piece lancet thatcan be fixedly secured in an end cap, separate from a driving member ofthe lancet assembly.

A yet further object of the present invention is to provide a new andimproved lancet assembly for piercing the skin of a user as painlesslyas possible in order to obtain blood for diagnostic test purposes.

Briefly, the present invention is directed to a new and improved devicecommonly referred to as a lancet assembly used for puncturing the skinof a user or patient to allow blood from the puncture to be tested. Thelancet assembly includes a base unit that defines a handle and houses aspring driven hammer. The hammer extends outward from one end of thebase unit and is cocked by merely pushing the hammer into the base unit.This action compresses a spring and latches the hammer within the baseunit.

The lancet assembly also includes a disposable end cap that can bedetachably secured to the base unit. The end cap includes an elongatedslot through which a lancet extends when struck by the hammer. Byrotating the end cap relative to the base unit, the slot is rotatedrelative to the finger of a user or a patient. In a first position ofthe end cap the lancet will penetrate deep into the skin of the user orpatient. In a second position of the end cap the lancet will penetrate ashallower depth into the skin of the patient or user.

The end cap includes integral resilient spring fingers formed on theinside of the end cap. A molded on piece lancet is positioned within theend cap against the spring fingers. When the end cap is attached to thebase unit and the hammer released, the hammer strikes the lancet drivingit through the slot in the end of the end cap. The resilient springfingers then act to return the lancet to a position totally within theend cap.

The lancet of the present invention includes a collar member withindexing structure. The indexing structure interfaces with complimentarystructure on the inner peripheral surface of the end cap to lock thelancet relative to the end cap such that the lancet will move with theend cap when the end cap is rotated to orientate the elongated slot. Thelancet also includes a piercing end that is driven into the skin of theuser or patient, and an anvil end that is struck by the hammer. Afterthe lancet has been used, the end cap can be easily removed or snappedoff of the base unit and no portion of the lancet is exposed outside ofthe end cap. In this condition, the end cap can be carried or handledwithout risk of puncturing the hand of the user and exposing the user tocontaminated blood.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages and novel features of thepresent invention will become apparent upon reading the followingdetailed description of a preferred embodiment of the inventionillustrated in the accompanying drawings wherein:

FIG. 1 is an exploded, enlarged, perspective view of a lancet assemblyconstructed in accordance with the objectives of the present invention;

FIG. 2 is a vertical cross sectional view of the end cap of the lancetassembly taken along line 2-2 in FIG. 1;

FIG. 3 is a vertical cross sectional view of the end cap taken alongline 3--3 in FIG. 1;

FIG. 4 is an enlarged, partially cross sectioned view of a lancet usedin the lancet assembly illustrated in FIG. 1;

FIG. 5 is an enlarged view similar to FIG. 2 with a lancet mountedwithin the end cap; and

FIG. 6 is an end view of the end cap with a lancet mounted therein.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will be described in detail herein. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theappended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to the drawings and specifically to FIG. 1; there isillustrated a lancet assembly generally designated by the referencenumeral 10. The lancet assembly 10 prevents accidental puncturing of theskin of a professional user of the assembly 10 such as a nurse or otherhealth care professional. The lancet assembly 10 includes two separatecomponents, a reusable base unit generally designated by the referencenumeral 12, and disposable end cap generally designated by the referencenumeral 14. The combination of a reusable base unit 12 with a disposableend cap 14 significantly reduces the cost of the lancet assembly 10 andincreases the safety to the user.

The end cap 14 is designed to house a lancet generally designated by thereference numeral 16. The base unit 12 houses a hammer 18 that engagesor strikes the lancet 16 and drives the lancet 16 into the skin of apatient or user. The hammer 18 differs from the typical driving memberin prior art lancet assemblies. The hammer 18 functions as a strikingelement, striking the lancet 16 as opposed to gripping the lancet andcarrying the lancet with the hammer. Instead of a gripping structure,the hammer 18 includes a flat striking face 26. By using a hammer 18instead of a driving member that grips the lancet 16, the lancet 16 doesnot need to extend out of the end cap 14 to be attached to the hammer18. Rather, the lancet 16 is located totally within the end cap 14. Thisincreases the safety of the lancet assembly 10 since once the lancet 16has been used and it is contaminated with blood or other body fluids,the end cap 14 can be disposed of without the danger of the contaminatedlancet 16 contacting the finger of the user.

The hammer 18 should be of considerably more mass than the lancet 16.Due to the greater mass, as the hammer 18 is accelerated towards thelancet 16 under the influence of a compressed spring 20 in the base unit12, the transference of linear momentum from the impact of the hammer 18gives the lancet 16 a high velocity in a direction outward of the endcap 14. The lancet 16 is then returned to a position completely withinthe end cap 14 by spring fingers 22, molded on the inside of the end cap14.

The base unit 12 is similar to prior art lancet assemblies. By pushingthe hammer 18 inwardly into the base unit 12, the spring 20 iscompressed and stores energy. As the hammer 18 is moved into the baseunit 12, the hammer 18 is latched in position and held within the baseunit 12 until a button 24 is pushed by a user. Pushing the button 24releases the hammer 18. The hammer 18 is then driven outwardly of thebase unit 12 under the biasing force of the spring 20.

The disposable end cap 14 includes an open end 28 which snaps over ahammer end 30 of the base unit 12. A snap or friction fit is provided byan inner peripheral rim 32 on the end cap 14. The engagement of the rim32 with the outer peripheral surface of the base unit 12 holds the endcap 14 onto the base unit 12 with the hammer 18 aligned to extend intothe open end 28 of the disposable end cap 14. To allow easy removal ofthe end cap 14 for disposal, a flange 34 is formed on the outerperiphery of the disposable end cap 14 adjacent the open end 28. Afterblood has been drawn, the user of the lancet assembly 10 may remove thedisposable end cap 14 merely by pushing against the flange 34 to movethe end cap 14 off the end 30 of the base unit 12.

The disposable end cap 14 includes a closed end 36 with an elongatedslot 38 formed in the closed end 36. The slot 38 is of a length that isgreater than its width. This slot 38 controls the depth of penetrationof the lancet 16 into the skin of a patient. More specifically, byaligning the length of the slot 38 with the length of a patent's finger,more of the patient's skin is moved into the slot 38 allowing deeperpenetration of the lancet 16 into the patient's finger. By rotating theend cap 14 such that the length of the slot 38 extends across the fingerof the patient, less skin enters into the slot 38 and shallowerpenetration of the lancet 16 into the skin results. Consequently, theuser of the lancet assembly 10 can control the depth of penetration ofthe lancet 16 into the skin of a patient by rotating the disposable endcap 14 relative to the base unit 12.

The user of the lancet assembly 10 can ascertain the orientation of theslot 38 by viewing the location of a pair of ribs 40 formed on oppositesides of the disposable end cap 14. The ribs 40 are aligned with theends of the longitudinal slot 38. By determining the location of theribs 40 relative to the finger of a patient, a user can determinewhether the lancet assembly 10 is aligned for deep or shallowpenetration.

The end cap 14 is designed to contain the lancet 16 entirely within itbefore and after use of a lancet assembly 10. The lancet 16 ismaintained within the end cap 14 before use and returned to a positionwithin the end cap 14 after use by the resilient spring fingers 22integrally molded on the inside of the end cap 14. Preferably, the endcap 14 is molded of polyethylene which is a flexible material allowingthe spring fingers 22 to be molded as a single piece with the end cap14. Polyethylene provides sufficient resilience to return the lancet 16to a position within the end cap after the lancet 16 has been struck bythe hammer 18.

The movement of the lancet 16 is guided by ribs 42 molded on theinterior of the end cap 14. The ribs 42 also function to index a flutedcollar 44 on the lancet 16. The fluted collar 44 includes arms or flutes46 that function as indexing structures by engaging the ribs 42 of theend cap 14. This engagement of the ribs 42 and arms 46 aligns the lancet16 within the end cap 14. The lancet 16 includes an anvil end 48 that isengaged by the hammer 18 to drive the lancet 16 through the slot 38 ofthe end cap 14. As this occurs, the ribs 42 engage the arms 46 guidingthe movement of the lancet 16 as driven by the hammer 18 and as returnedto its original position by the spring fingers 22. In addition, theengagement of the indexing structure as defined by the ribs 42 and arms46 allows the lancet 16 to rotate with the end cap 14 as the end cap 14is rotated relative to the base unit 12 to align the slot 38 with thelength or width of a finger of a patient.

In one embodiment of the present invention, a user purchases the baseunit 12 and can use the base unit many times before replacement isnecessary. The disposable end caps 14 are purchased in quantity. The endcaps 14 include the lancet 16 already assembled within the end cap 14.The lancet 16 is located within the end cap 14 with the arms 46 engagingthe ribs 42. A flange 50 on the fluted collar 44 is snapped behind snaps52 (FIG. 3) formed on the inner peripheral surface of the end cap 14.The snaps 52 hold the lancet 16 within the end cap 14 and prevent itfrom falling out the open end 28 prior to attaching the end cap 14 tothe base unit 12.

The lancet 16 includes a needle or other sharp object 54 that piercesthe skin of a patient. Prior to actual use, the needle 54 is covered bya needle plug 56. The needle plug 56 is made of a soft material intowhich the needle 54 extends. The needle plug 56 includes a flat gripingsurface 58 that extends through the slot 38 when the lancet 16 ismounted or assembled within the end cap 14. To use the lancet assembly10, a user snaps a disposable end cap 14 onto the base unit 12. The userthen grips the gripping surface 58 of the needle plug 56, and withslight pulling pressure removes the needle plug 56 from the needle 54.The spring fingers 22 then move the lancet 16 inside the end cap 14 suchthat the needle 54 is safely within the end cap 14. The lancet 16 isalso held into position within the end cap 14 by the snaps 52 such thatthe anvil end 48 of the lancet 16 does not extend through the open end28 of the end cap 14. Thus, while the end cap 14 is attached to the baseunit 12, no portion of the lancet 16 is exposed outside the end cap 14.

Once the end cap 14 has been snapped onto the base unit 12 and theneedle plug 56 removed from the needle 54, the user may push the button24 to release the hammer 18 under the influence of the spring 20. Thehammer 18 strikes the anvil end 48 of the lancet 16 driving the lancet16 against the spring fingers 22. The needle 54 moves through the slot38 and into the skin of a patient. Once the momentum of the hammer 18has been exhausted, the spring fingers 22 quickly return the needle 54to the position illustrated in FIG. 5. In this position, the needle 54is completely within the end cap 14. After a sample of blood has beendrawn, the user may snap off the disposable end cap 14 merely byengaging the flange 34 with a thumb and popping or snapping the end cap14 off the base unit 12. The spring fingers 22 and the snaps 52 hold thelancet 16 entirely within the end cap 14. Since the hammer 18 strikesthe lancet 16 rather than gripping it, the anvil end 48 of the lancet 16does not extend outside of the end cap 14. The contaminated disposableend cap 14 can then be handled by the user without the danger ofengaging the contaminated needle 54, or hitting the anvil end 48 andpushing the needle 54 outside the end cap 14 where it can puncture theskin of the person handling the end cap 14.

Another advantage of the spring fingers 22 is that they cause the needle54 to be quickly retracted from the skin of a patient and this resultsin less pain for the patient.

The lancet assembly 10 of the present invention provides increasedsafety for the user by totally containing the contaminated lancet 16within the end cap 14. After the lancet 16 has been used and the end cap14 removed from the base unit 14, there is no portion of the lancet 16outside the end cap 14 that can be engaged by the user during handling.Consequently, the contaminated needle 54 cannot be contacted by the userand disposal of the end cap 14 can be accomplished safely.

What is claimed and sought in United States Letters Patent is:
 1. Alancet for a lancet assembly for piercing skin of a user upon engagementby a hammer housed in said lancet assembly, said lancet comprising:afirst, skin piercing end for piercing the skin of a user of the lancetassembly upon said lancet being driven by a hammer in said lancetassembly, a second, anvil end adapted for engagement by said hammer, anda collar intermediate said first, skin piercing end and said second,anvil end, said collar including orienting structure for orienting saidlancet in said lancet assembly and for preventing rotation of saidlancet relative to said lancet assembly.
 2. The lancet set forth inclaim 1 further comprising a flange on said collar for engaging saidlancet assembly to limit the travel of said lancet in said lancetassembly upon engagement by said hammer.